This project aims to develop new multi-lethal antibiotics capable of combating resistant and persistent S. aureus infections of the skin and soft tissue. Antibiotic-resistant infections are a global health concern and they are associated with 2 million illnesses and 23,000 deaths in the United-States every year resulting in $20 billion in excess health care costs and an additional $35 billion in lost productivity. There is urgent need for new approaches. To address this problem, we designed a new class of antibiotics; membrane-active aminoglycoside-peptide conjugates (MAAPC) that combines an aminoglycoside antibiotic that targets bacterial ribosomes and a short peptide sequence that enables the MAAPC to selectively disrupt the barrier function of bacterial membranes. Aminoglycosides are potent antibiotics, but they have limited activity against many clinical pathogens due to a low cellular uptake. In contrast, because membrane-active antimicrobial peptides (AMPs) permeabilize membranes they are broad spectrum antimicrobials but often display moderate activity. By combining the membrane activity of AMPs with the ribosomal activity of aminoglycosides, MAAPCs have multiple levels of selectivity and multiple mechanisms of killing. Our first prototype, Pentobra, exhibits broad spectrum antimicrobial activity and kills bacteria that tolerate conventional antibiotics. Additionally, its killing activty can be potentiated by the co-delivery of saccharides. We propose to combine the synergistic antimicrobial actions of Pentobra with a glycomimetic polymer, either in mixtures or as a conjugate to form a single multi-lethal molecule. To implement this plan, we will: (1) Synthesize a series of glycomimetic polymers for co-delivery with or conjugation to Pentobra, our prototyope MAAPC. We will evaluate the enzymatic and hydrolytic stability of the glycomimetic polymers against bacterial enzymes, and characterize the interaction of the new conjugates with model bacterial and mammalian membranes. (2) The killing efficiency of mixtures and conjugates of glycomimetics with Pentobra will be tested in vitro on persistent S. aureus. This work will rely on a multidisciplinary team led by Dr. Andrea Kasko and Dr. Gerard Wong. The expertise of Dr. Kasko in chemical synthesis will be combined with that of Dr. Wong in antimicrobial-membrane interactions and bacteriology. MAAPCs have the capacity to expand drastically the spectrum of activity of the potent class of aminoglycoside antibiotics (ex: against anaerobic bacteria, persistent and resistant bacteria expand activity of Gram negative antibiotics to Gram positive bacteria). The glycomimetic polymers have never been utilized previously as aminoglycoside potentiators, and using a macromolecular chain instead of small molecules allows direct conjugation to MAAPCs to produce a single-molecule antimicrobial with multiple synergistic functions. The success of this project will provide new alternatives to treat antibioti-resistant infections.